Radio-Frequency Identification (RFID) has been used in manufacturing and warehouse management for years to identify and track everything from inventories to cattle. RFID uses tags or labels attached to the objects to be identified. Two-way radio transmitter-receivers, called interrogators or readers, send a signal to the tag and read its response. The benefits are that it can be attached to or embedded in the tracked object.

There are three types of tags and readers. A Passive Reader Active Tag (PRAT) system has a passive reader which only receives radio signals from active tags (battery operated, transmit only). An Active Reader Passive Tag (ARPT) system has an active reader, which transmits interrogator signals and also receives authentication replies from passive tags. An Active Reader Active Tag (ARAT) system uses active tags activated with an interrogator signal from the active reader. A variation of this system could also use a Battery-Assisted Passive (BAP) tag which acts like a passive tag but has a small battery to power the tag’s return reporting signal.

Near-Field Communication (NFC) is based on the RFID protocols. The main difference to RFID is that a NFC device can act as a reader, and also as a tag. In peer-to-peer mode, it is also possible to transfer information between two NFC devices. NFC systems operate on the same frequency range as RFID, however there are short-range limitations making it more secure. NFC is designed as “approved communication” between two partners and it is not designed to be used as a tracking device like RFID. NFC devices have to be in very close proximity, usually no more than a few centimeters to about four inches, which is why you see it used in contactless payment with a mobile phone.